Tensions running high

Sri Lankan police said petrol bombs were hurled at a mosque on Thursday as hundreds of troops patrolled a troubled central district where anti-Muslim violence has left three people dead.

Muslim-owned businesses were set on fire and vandalised in several parts of Sri Lanka, police said, days after an island-wide state of emergency was imposed to curb riots in Kandy.

Police announced 85 people had been arrested for rioting in the hill district, including the leader of a radical Sinhalese Buddhist group known for agitating against Muslims.

"We have arrested 10 key suspects, including Amith Weerasinghe, who orchestrated and led these attacks," police spokesman Ruwan Gunasekera told reporters in Colombo, adding that another 75 were detained.

Armoured vehicles and heavily-armed troops guarded Kandy, the epicentre of the violence where internet services remain suspended and an evening curfew is in place.

The government ordered the internet blackout after police discovered mobs of Sinhalese rioters were using social media to coordinate attacks on Muslim establishments.

More than 200 homes, businesses and vehicles have been torched in three days of violence by mobs from the mainly Buddhist Sinhalese majority.

A 24-hour curfew was imposed on Wednesday afternoon after a hand grenade exploded in the hands of an attacker, killing him and wounding 11 others, officials said.

The day-time curfew was eased following a calm night but schools were shuttered as tensions remain high in the tourist hotspot.

In Kuruvita, 125 kilometres south of Kandy, police said petrol bombs were lobbed at a mosque. Little damage was inflicted and three suspects are being pursued.

In Weligama, 240 kilometres south of Kandy, a Muslim-owned business was attacked, police said, while Muslim establishments were pelted with stones in at least two other locations outside Kandy.

President Maithripala Sirisena toured Kandy on Wednesday and ordered security forces to use the full force of the law against troublemakers.

Military officials said more reinforcements were sent to the area on Wednesday night to assist police who resorted to teargas to disperse rioters the previous evening.

The United Nations has condemned the violence and urged Colombo "to ensure that appropriate measures are swiftly taken to restore normalcy in affected areas".